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Piston Compression Height
What compression piston do I need?
Click on the list below to take you to the various calculations on this page:
Before selecting a piston, the desired compression height must be known. As shown, compression height is the distance between the centerline of the pin bore and the top of the piston. To determine the compression, three things about the engine must first be known: block height, connecting rod length and crankshaft stroke length.
1. Calculate Block Height
Deck height is measured from the crankshaft centerline to the deck (cylinder head mounting surface) of the block.
| Displacement Cubic Inches | Liters | Deck Height (in) | |
|---|---|---|---|
| STOCK CHEVY V8 BLOCK HEIGHTS | |||
| 302 | 4.9 | 9.025 | |
| 305 | 5.0 | 9.025 | |
| 327 | 5.4 | 9.025 | |
| 350 | 5.7 | 9.025 | |
| 350(LT5) | 5.7 | 9.025 | |
| 350(LS1) | 5.7 | 9.240 | |
| 364(LQ4) | 6.0 | 9.240 | |
| 383 | 6.3 | 9.025 | |
| 400 | 6.6 | 9.025 | |
| 396 | 6.5 | 9.800 | |
| 402 | 6.6 | 9.800 | |
| 427 | 7.0 | 9.800 | |
| 454 | 7.4 | 9.800 | |
| 502 | 8.2 | 9.800 | |
| Displacement Cubic Inches | Liters | Deck Height (in) | |
|---|---|---|---|
| STOCK FORD V8 BLOCK HEIGHTS | |||
| 289 | 4.7 | 8.206 | |
| 302 | 5.0 | 8.206 | |
| 302(Boss) | 5.0 | 8.201-8.210 | |
| 302(SVO) | 5.0 | 8.201-8.210 | |
| 351W ('69-'70) | 5.8 | 9.480 | |
| 351W ('71-'96) | 5.8 | 9.503 | |
| 351 (SVO 9.2) | 5.8 | 9.206 | |
| 351C (Boss) | 5.8 | 9.206 | |
| 351M | 5.8 | 10.297 | |
| 429 STD ('68-'70) | 7.0 | 10.300 | |
| 429 STD ('70 1/2-'71) | 7.0 | 10.310 | |
| 429 CJ/SCJ ('72-'73) | 7.0 | 10.322 | |
| 429 Boss (S) | 7.0 | 10.300 | |
| 429 Boss (T) | 7.0 | 10.300 | |
| 460 ('72-'96) | 7.5 | 10.322 | |
| 4.6L (281)-5.0L (302) Modular | 4.6/5.0L | 8.937 | |
| 5.4L (330) Modular | 5.4 | 10.079 | |
2. Calculating Connecting Rod Length
Connecting rod length is measured between the centers of the "big end" (journal end - rotating) and the "little end" (piston pin end - reciprocating).
| Displacement Cubic Inches | Liters | Big End Dia. (in) | Rod Length (in) |
|---|---|---|---|
| STOCK CHEVY V8 CONNECTING ROD LENGTHS | |||
| 302 | 4.9 | 2.1000 | 5.7000 |
| 305 | 5.0 | 2.1000 | 5.7000 |
| 327 | 5.4 | 2.1000 | 5.7000 |
| 350 | 5.7 | 2.1000 | 5.7000 |
| 350(LT5) | 5.7 | 2.1000 | 5.7400 |
| 350(LS1) | 5.7 | 2.2500 | 6.0980 |
| 383 | 6.3 | 2.1000 | 6.0000 |
| 400 | 6.6 | 2.1000 | 5.5650 |
| 396 | 6.5 | 2.2000 | 6.1350 |
| 402 | 6.6 | 2.2000 | 6.1350 |
| 427 | 7.0 | 2.2000 | 6.1350 |
| 454 | 7.4 | 2.2000 | 6.1350 |
| 502 | 8.2 | 2.2000 | 6.1350 |
| Displacement Cubic Inches | Liters | Big End Dia. (in) | Rod Length (in) |
|---|---|---|---|
| STOCK FORD V8 CONNECTING ROD LENGTHS | |||
| 289 | 4.7 | 2.1232 | 5.1550 |
| 302 | 5.0 | 2.1232 | 5.0900 |
| 302 (Boss) | 5.0 | 2.1226 | 5.1500 |
| 302 (SVO) | 5.0 | 2.1226 | 5.1500 |
| 351 W (1969-70) | 5.8 | 2.3110 | 5.9560 |
| 351 W (1971-96) | 5.8 | 2.3110 | 5.9560 |
| 351 (SVO 9.2) | 5.8 | 2.3110 | 5.7800 |
| 351C (Boss) | 5.8 | 2.3110 | 5.7800 |
| 351M | 5.8 | 2.3107 | 6.5800 |
| 429 STD (1968-70) | 7.0 | 2.500 | 6.6050 |
| 429 STD (1970 1/2-71) | 7.0 | 2.500 | 6.6050 |
| 429 CJ/SCJ (1972-73) | 7.0 | 2.500 | 6.6050 |
| 429 Boss (S) | 7.0 | 2.500 | 6.5490 |
| 429 Boss (T) | 7.0 | 2.500 | 6.6050 |
| 460 | 7.5 | 2.500 | 6.6050 |
| 281 (Modular) | 4.6 | 2.0863 | 5.9331 |
| 331 (Modular) | 5.4 | 2.0863 | 6.6575 |
3. Calculate Stroke Length
Stroke length is twice the distance from the centerline of the crankshaft main bearing journals to the centerline of the connecting rod journals. It is also the distance the piston moves up and down in the cylinder.
| Displacement Cubic Inches | Liters | Bore (in) | Stroke (in) |
|---|---|---|---|
| STOCK CHEVY V8 BORE & STROKE | |||
| 302 | 4.9 | 4.000 | 3.000 |
| 305 | 5.0 | 3.740 | 3.480 |
| 327 | 5.4 | 4.000 | 3.250 |
| 350 | 5.7 | 4.000 | 3.480 |
| 350(LT5) | 5.7 | 3.898 | 3.661 |
| 350(LS1) | 5.7 | 3.898 | 3.622 |
| 364(LQ4) | 6.0 | 4.000 | 3.622 |
| 383 | 6.3 | 4.000 | 3.800 |
| 400 | 6.6 | 4.125 | 3.750 |
| 396 | 6.5 | 4.094 | 3.766 |
| 402 | 6.6 | 4.125 | 3.766 |
| 427 | 7.0 | 4.250 | 3.766 |
| 454 | 7.4 | 4.250 | 4.000 |
| 502 | 8.2 | 4.470 | 4.000 |
| Displacement Cubic Inches | Liters | Bore (in) | Stroke (in) |
|---|---|---|---|
| STOCK FORD V8 BORE & STROKE | |||
| 289 | 4.7 | 4.000 | 2.870 |
| 302 | 5.0 | 4.000 | 3.000 |
| 302(Boss) | 5.0 | 4.000 | 3.000 |
| 302(SVO) | 5.0 | 4.000 | 3.000 |
| 351 W ('69-'70) | 5.8 | 4.000 | 3.500 |
| 351 W ('71-'96) | 5.8 | 4.000 | 3.500 |
| 351 (SVO 9.2) | 5.8 | 4.000 | 3.500 |
| 351C (Boss) | 5.8 | 4.000 | 3.500 |
| 351M | 5.8 | 4.000 | 3.590 |
| 429 STD ('68-'70) | 7.0 | 4.360 | 6.6050 |
| 429 STD ('70 1/2-'71) | 7.0 | 4.360 | 3.590 |
| 429 CJ/SCJ ('72-'73) | 7.0 | 4.360 | 3.590 |
| 429 Boss (S) | 7.0 | 4.360 | 3.590 |
| 429 Boss (T) | 7.0 | 4.360 | 3.590 |
| 460 | 7.5 | 4.360 | 3.850 |
| 281 (modular) | 4.6 | 3.543 | 5.9331 |
| 331 (modular) | 5.4 | 3.552 | 4.165 |
How Compression Height Is Calculated:
| Compression height = block height - rod length - (0.5 X stroke) | ||
| Example: | block height = 11.685 | |
| rod length = 7.500 | ||
| stroke = 5.500 | ||
| Compression height = block height - rod length - (0.5 X stroke) | ||
| Compression height = 11.685 - 7.500 - (0.5 X 5.500) | ||
| Compression height = 1.435 | ||